Clinical signs of trachoma and laboratory evidence of ocular Chlamydia trachomatis infection in a remote Queensland community: a serial cross-sectional study

Objectives: To compare the findings of standard clinical assessments and of complementary clinical and laboratory methods for determining whether community-wide treatment for trachoma is warranted in a remote Queensland community. Design: Three cross-sectional screening surveys, 2019–2021, complemented by laboratory pathology testing. Setting: Small community in northwest Queensland with geographic and cultural ties to Northern Territory communities where trachoma persists. Participants: Children aged 1–14 years; opportunistic screening of people aged 15 years or more. Main outcome measures: Prevalence of clinical signs of trachoma, Chlamydia trachomatis infection, ocular non-chlamydial infections, and seropositivity for antibodies to the C. trachomatis Pgp3 protein. Results: During the three surveys, 73 examinations of 58 children aged 1–4 years, 309 of 171 aged 5–9 years, and 142 of 105 aged 10–14 years for trachoma were undertaken, as were 171 examinations of 164 people aged 15 years or more; 691 of 695 examinations were of Aboriginal or Torres Strait Islander people (99%), 337 were of girls or young women (48%). Clinical signs consistent with trachomatous inflammation–follicular were identified in 5–9-year-old children 23 times (7%), including in eleven with non-chlamydial infections and one with a C. trachomatis infection. One child (10–14 years) met the criteria for trachomatous scarring. Two of 272 conjunctival swab samples (all ages) were polymerase chain reaction-positive for C. trachomatis (0.7%). Two of 147 people aged 15 years or more examined in 2019 had trichiasis, both aged 40 years or more. Seven of 53 children aged 1–9 years in 2019 and seven of 103 in 2021 were seropositive for anti-Pgp3 antibodies. Conclusions: Despite the prevalence of clinical signs consistent with trachomatous inflammation–follicular among 5–9-year-old children exceeding the 5% threshold for community-wide treatment, laboratory testing indicated that childhood exposure to ocular C. trachomatis is rare in this community. Laboratory testing should be integrated into Australian trachoma guidelines.Full Tex